Comments on: Paradigm upended? http://oklo.org/2010/04/19/paradigm-upended/ characterizing planetary systems Fri, 18 Nov 2011 22:27:52 +0000 hourly 1 http://wordpress.org/?v=3.2.1 By: Eric Jensen http://oklo.org/2010/04/19/paradigm-upended/comment-page-1/#comment-33927 Eric Jensen Tue, 20 Apr 2010 16:33:50 +0000 http://oklo.org/?p=1137#comment-33927 Very interesting results. Regarding the plausibility of a planetary system having such a high inclination to the binary orbit, my collaborators and I tried to go at it from another direction, looking at protoplanetary disks in young binaries, to probe the orientation of the raw material before it forms planets. We found (Jensen et al. 2004, http://adsabs.harvard.edu/abs/2004ApJ...600..789J) that disks in binaries tend to be aligned with each other. Now, we couldn't measure the binary orbital plane directly in these wide (and thus long-period) systems, with separations of 200 AU to 1000 AU. But the fact that the two disks lie near the same plane is suggestive of that also being the binary orbital plane. If so, then Kozai migration would not be very effective in these systems. Interestingly, we also found that disks in triple star systems tend *not* to be aligned, presumably because the closer companion (which we didn't resolve) has more of an influence on the nearby disk than the wider companion does. Applying these results to the planetary systems, this could suggest a scenario in which the mis-aligned planets form more like stars, i.e. by fragmentation during collapse, while the aligned planets (perhaps) form later, from core accretion in disks. It's hard to say if this formation scenario is correct, but the disk alignment data provide another piece of data for the puzzle. Thanks again for an interesting post. Very interesting results. Regarding the plausibility of a planetary system having such a high inclination to the binary orbit, my collaborators and I tried to go at it from another direction, looking at protoplanetary disks in young binaries, to probe the orientation of the raw material before it forms planets. We found (Jensen et al. 2004, http://adsabs.harvard.edu/abs/2004ApJ…600..789J) that disks in binaries tend to be aligned with each other. Now, we couldn’t measure the binary orbital plane directly in these wide (and thus long-period) systems, with separations of 200 AU to 1000 AU. But the fact that the two disks lie near the same plane is suggestive of that also being the binary orbital plane. If so, then Kozai migration would not be very effective in these systems.

Interestingly, we also found that disks in triple star systems tend *not* to be aligned, presumably because the closer companion (which we didn’t resolve) has more of an influence on the nearby disk than the wider companion does. Applying these results to the planetary systems, this could suggest a scenario in which the mis-aligned planets form more like stars, i.e. by fragmentation during collapse, while the aligned planets (perhaps) form later, from core accretion in disks.

It’s hard to say if this formation scenario is correct, but the disk alignment data provide another piece of data for the puzzle. Thanks again for an interesting post.

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